The present invention relates to a decorative material for use, for example, in surface materials including decorative sheets, such as building interior materials including walls, and surface materials of, for example, fittings, such as doors, and furniture. More particularly, the present invention relates to a decorative material which has a surface resin layer formed from an ionizing radiation curable resin and can realize, at low cost, staining resistance and marring resistance, as well as abrasion resistance, scratch resistance, anti-transferability to a cellophane pressure-sensitive adhesive tape and other surface properties.
Abrasion resistance, staining resistance and other surface properties are generally required of decorative materials, such as decorative sheets for use, for example, in interior materials. In order to meet this demand, for example, decorative materials having a surface layer formed from a two-component curable urethane resin is generally used. The use of the two-component curable urethane resin, however, sometimes results in the formation of a surface resin layer possessing unsatisfactory staining resistance and unsatisfactory marring resistance (particularly resistance to scratch of a glossy surface).
Accordingly, a decorative material having a surface layer formed from an ionizing radiation curable resin has also been used, for example, from the viewpoints of higher crosslinking density and higher curing speed as compared with the two-component curable urethane resin. For example, Japanese Patent Publication Nos. 31033/1974 and 22694/1992 disclose a decorative material which has been formed by forming a pattern layer on a substrate by printing, coating an unsaturated polyester, acrylate or other ionizing radiation curable resin coating composition on the surface to form a coating as the outermost surface layer, and then crosslinking and curing the coating by an electron beam to form a surface resin layer. The use of an ionizing radiation curable resin in the formation of the surface layer can more easily provide staining resistance, marring resistance and the like which are unsatisfactory in the case of the two-component curable urethane resin.
Even when the ionizing radiation curable resin is used in the formation of the surface resin layer, better surface properties, for example, in terms of staining resistance, marring resistance, and, in addition, abrasion resistance, scratch resistance, anti-transferability to a cellophane pressure-sensitive adhesive tape are sometimes required. This requirement has been met, for example, by a method (A) wherein spherical particles, such as spherical xcex1-alumina, is added to the ionizing radiation curable resin coating composition for the surface layer (see Japanese Patent No. 2740943), or by a method (B) wherein, when the substrate is paper, a resin impregnated paper with an acrylic resin, rubber latex or the like being impregnated thereinto is provided and a pattern layer is printed on this substrate.
The decorative materials produced by the methods (A) and (B) certainly have improved surface properties. Since, however, special materials are used, the production cost is so high that the applications of these decorative materials are disadvantageously limited. An attempt to form the surface resin layer from the two-component curable urethane resin instead of the ionizing radiation curable resin from the viewpoint of the cost has in many cases resulted in unsatisfactory surface properties, particularly unsatisfactory staining resistance and marring resistance.
For this reason, the development of a decorative material, which can be produced at low cost and, at the same time, possesses excellent surface properties such as excellent staining resistance, marring resistance, abrasion resistance, scratch resistance, and anti-transferability to a cellophane pressure-sensitive adhesive tape, has been desired in the art.
In order to solve the above problems of the prior art, according to the present invention, there is provided a decorative material comprising: a substrate having at least on its surface an active hydrogen-containing polar functional group; and, provided on the substrate, a two-component cured urethane resin layer and a surface resin layer of a crosslinked coating formed from a ionizing radiation curable acrylate resin, said two-component cured urethane resin layer having a structure of at least three layers of a first resin layer, a second resin layer, and a third resin layer provided in that order from the substrate side, the crosslinking density of the second resin layer being lower than that of the first resin layer and that of the third resin layer.
By virtue of the above construction, the decorative material according to the present invention can realize low cost and, at the same time, excellent surface properties such as excellent staining resistance, marring resistance, scratch resistance, abrasion resistance, and anti-transferability to a cellophane pressure-sensitive adhesive tape. These excellent properties of the decorative material according to the present invention are considered attributable to the following reasons.
(1) When the two-component curable urethane resin cure, the active hydrogen-containing polar functional group present on the surface of the substrate is chemically reacted with an isocyanate component in the two-component curable urethane resin to form a chemical bond which can improve the adhesion of the substrate to a layer formed from the two-component curable urethane resin.
(2) The adoption of an acrylic resin as the ionizing radiation curable resin permits a resin material, which can cope with required properties, to be easily available at relatively low cost.
(3) The adhesion between the two-component cured urethane resin layer and the substrate and the adhesion between the two-component cured urethane resin layer and the surface resin layer can be improved, and the modulus of elasticity can be lowered by the second resin layer having relatively low crosslinking density to improve the marring resistance, the scratch resistance, and abrasion resistance.
(4) Even though a contaminant, such as a dye, has penetrated the interior of the assembly without being fully blocked by the surface resin layer, the portion having relatively high crosslinking density (third resin layer) can receive the contaminant and thus can prevent further penetration and can improve the staining resistance.
In the decorative material having the above construction according to the present invention, preferably, the polyol component for the formation of the two-component cured urethane resin layer is a two-component system of an unsaturated polyester polyol and a saturated polyester elastomer polyol.
The use of the specific polyol component in the formation of the two-component cured urethane resin layer can easily improve the modulus of elasticity of the two-component cured urethane resin layer, and, in addition, can further improve the adhesion between the two-component cured urethane resin and the surface resin layer. This is considered attributable to the fact that the unsaturated polyester polyol contained in the polyol component takes part in a crosslinking reaction with the ionizing radiation curable acrylate resin at the time of the formation of the surface resin layer, and, thus, the resultant chemical bond can provide intimate adhesion between the surface resin layer and the two-component cured urethane resin layer. Another reason of improved adhesion is considered that the saturated polyester elastomer polyol having a soft segment give the modulus of elasticity to the two-component cured urethane resin layer.
Further, in any one of the above constructions in the decorative material according to the present invention, preferably, the ionizing radiation curable resin for the surface resin layer further contains silicone (meth)acrylate.
This construction can surely realize better anti-transferability to a cellophane pressure-sensitive adhesive tape and abrasion resistance as compared with the use of conventional lubricants such as silicone resin.